New job listings on the official Respawn Entertainment website could be hinting to a new action series unrelated to Titanfall. The openings in question are Senior Animator and a Senior Character Artist, with "experience working on 3rd person action/exploration games" being listed as a requirement for both.
Job listings tend to be categorized as rumors until some official word is released, but they're certainly credible enough to take note of. In addition to the recently discovered (and rather specific) listings, Respawn also welcomed God of War creative director Stig Asmussen into their ranks this month.
Respawn co-founder Vince Zampella even confirmed Asmussen's new role with the Titanfall studio as a game director for an unnamed project. Given his background working on Sony's iconic God of War series, the whole "3rd person action/exploration" bit starts to make more sense. Then again, all of this is just conjecture right now.